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ENERGY STAR® is a U.S. Environmental Protection Agency
program helping businesses and individuals fight global
warming through superior energy efficiency.
International Efficiency Marking Protocol for External Power Supplies
This fact sheet describes the international efficiency marking protocol and its implementation
under the ENERGY STAR Version 2.0 External Power Supply specification. Sources for additional
information are provided on page 3. This version, updated as of October 2008, replaces an earlier
document released in 2005.
What is the international efficiency marking protocol?
The international efficiency marking protocol provides a system for power supply manufacturers to
designate the minimum efficiency performance of an external power supply, so that finished product
manufacturers and government representatives can easily determine a unit's efficiency. This mark does
not serve as a consumer information label, but rather demonstrates the performance of the external
power supply when tested to the internationally supported test method (this test method titled "Test
Method for Calculating the Energy Efficiency of Single-Voltage External Ac-Dc and Ac-Ac Power Supplies
(August 11, 2004)" can be found at www.eneravstar.gov/powersupplies').
What does the international efficiency mark look like?
The international efficiency mark consists of a Roman numeral (I - VI) that corresponds to specific
minimum Active and No-Load efficiency levels (as well as a power factor requirement for level V) and is
printed/applied by the manufacturer on the external power supply nameplate (or an equally visible
location).
Format: Roman numeral: I, II, III, IV, V, or VI.
Font: Times Roman preferred (or other plain serif fonts).
Size: Legible and indelible.
Color: Text to contrast with the nameplate background, unless incorporated in the case molding.
Placement: Preferably on the power supply nameplate; however, exact location is at the discretion of
the manufacturer. The text "Efficiency Level" shown below is optional. An example is
provided below.
Brand
BATTERY CHARGER tor use with
Information Technology Equipment
AWARNING
For uh with rechargeable
LKort Battery Pack EN-ELI.
££ ©N999
- {5) IV02123
EFFICIENCY LEVELs©
How is the international efficiency marking protocol being implemented?
The nameplate (or an equally visible location) of single voltage external ac-dc and ac-ac power supplies
must be clearly and permanently marked with a Roman numeral from the sequence I (least efficient) to VI
(most efficient) that corresponds to specific minimum Active and No-Load efficiency levels (as well as a
power factor requirement for level V). The performance requirements for each Roman numeral are shov/n
in the table below.
To determine the appropriate Roman numeral, manufacturers: 1) compare the unit's Active, No-Load, and
power factor test data (when tested in accordance with the ENERGY STAR Test Method and at each
relevant test voltage and frequency value) with the performance requirements at each level of the Roman
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numeral scale; and 2) choose the highest Roman numeral where the power supply meets the Active, No-
Load, and power factor (where applicable) requirements.
Mark
Performance Requirements
Nameplate Power
Output (Pno)1
No-Load
Power2
Nameplate
Power Output
(Pno)
Average Active Efficiency^
Power Factor
I
Used if none of the other criteria are met.
II
0 to < 10 watts
<0.75
0 to < 1 watt
S 0.39 X Pno
> 10 to 250 watts
< 1.0
1 to < 49 watts
> 0.107 xLn(Pno)+ 0.39
Not applicable
>49 watts
>0.82
III
0 to < 10 watts
<0.5
0 to 1 watt
> 0.49 X Pno
10 to 250 watts
<0.75
> 1 to 49 watts
> 0.09 x Ln(Pno)+0.49
Not applicable
> 49 to 250 watts
>0.84
IV
0 to 250 watts
<0.5
0 to < 1 watt
> 0.5 X Pno
1 to 51 watts
> 0.09 x Ln(Pno)+0.5
Not applicable
> 51 to 250 watts
>0.85
V
0 to < 50 watts
<0.5 for ac-ac;
<0.3 for ac-dc
0 to < 1 watt
Standard: > 0.480 * Pno + 0.140
Low Voltage4: > 0.497 * Pno + 0.067
Power supplies
with greater
than or equal
> 50 to < 250 watts
<0.5
> 1 to < 49 watts
Standard: > [0.0626 * Ln (Pno)] + 0.622
Low Voltage: > [0.0750 * Ln (Pno)l + 0.561
to 100 watts
input power
> 49 to 250 watts
Standard: > 0.870
Low Voltage: > 0.860
must have a
true power
factor of 0.9 or
greater at
100% of rated
load when
tested at 115
volts @ 60Hz.
VI
and
higher
Reserved for future use.
What is the relationship between the international efficiency marking protocol and ENERGY
STAR?
The ENERGY STAR program for External Power Supplies requires that manufacturers mark their power
supplies using the international efficiency marking protocol. Any external power supply meeting the
performance requirements for level V and above would qualify as ENERGY STAR (Version 2.0). Power
supplies with performance levels of I - IV would not qualify under the Version 2.0 ENERGY STAR
specification, which takes effect on November 1, 2008.
The new federal US standard for external power supplies (effective July 1, 2008) is identical to level IV
above. This standard only requires compliance at 115 V/60 Hz.
1 Pno is the Nameplate Output Power of the unit under test.
2 In Australia and New Zealand, AC-AC external power supplies are not required to meet the no load power
requirements.
3 Ln refers to the natural logarithm.
4 A low voltage model is an EPS with a nameplate output voltage of less than 6 volts and a nameplate output current
greater than or equal to 550 milliamps.
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What if my power supply meets different efficiency levels when tested at different
voltage/frequency combinations?
To qualify as ENERGY STAR, manufacturers are required to mark the nameplate (or an equally visible
location') with the highest Roman numeral that the external power supply meets for Active and No-Load
requirements at both voltage/frequency combinations (115 V/60 Hz and 230 V/50 Hz). EPA also has a
power factor requirement under its Version 2.0 specification that only applies to power supplies with
greater than or equal to 100 watts input power and when tested at 115 V/60 Hz.
Some organizations such as Australia's Department of the Environment, Heritage and Arts (DEWHA), as
well as the US Energy Independence and Security Act of 2007, have adopted a modified approach to this
protocol, allowing manufacturers to mark an EPS capable of operating at multiple voltages/frequencies as
meeting the requirements in only one voltage/frequency combination. This modified approach is not
acceptable for marking a power supply for ENERGY STAR qualification, given the requirement to test and
qualify power supplies capable of operating at multiple voltages/frequencies at both 115 V/60Hz and 230
V/50 Hz. For illustrative purposes, the table below provides some sample marks and an explanation of
each.
Sample Marks
Explanation
Q
Mark indicating a power supply meets the level V requirements at both
115 V/60 Hz and 230 V/50 Hz, if designed to operate at multiple input
voltages. Products with a nameplate marked for only one voltage and
frequency should also use this mark assuming the product meets the
performance requirements; in other words, manufacturers do not have
to indicate the voltage with the mark.
©
Mark indicating a power supply meets the level V performance
requirements only at 115 V/60 Hz (for power supplies also able to
operate at 230 V/50 Hz). This mark shows compliance with the US
mandatory standard, but not with the ENERGY STAR Version 2.0
specification.
©
Mark indicating a power supply meets the level IV performance
requirements only at 115 V/60 Hz (for power supplies also able to
operate at 230 V/50 Hz). This mark shows compliance with the US
mandatory standard.
©
Mark indicating a power supply meets the level IV requirements at only
230 V/50 Hz (for power supplies also able to operate at 115 V/60 Hz).
This would be relevant for the Australian and New Zealand markets as
their MEPS and High Efficiency performance requirements and
mandatory marking only require testing and compliance at 230 V ac.
A,
Dual marking for a power supply that meets different performance
levels at different input voltages.
© An
For More Information
• On ENERGY STAR: Visit the ENERGY STAR Web site at www.energystar.gov/powersupplies or
contact Andrew Fanara, US EPA, at Fanara.andrew@epa.gov.
• On US energy conservation standards: Visit the US Department of Energy (DOE) Web site at
http://www.eere.energy.gov/buildings/appliance standards/residential/batterv external.html or
contact Victor Petrolati, US DOE, at Victor.Petrolati@ee.doe.gov.
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